Abstract
•Interaction of bio-cleavable surfactant (16-E2-16) with amphiphilic drug.•Surface tension, UV–visible, and FT-IR methods were employed.•Effect of NaCl/urea/thiourea on cmc of pure and mixed systems was studied.•UV–visible/FTIR study also confirmed interaction between drug and surfactant.•Mixed micelles formation enhances solubility, so propitious for drug delivery.
Ester bonded bio-cleavable gemini surfactant - ethane-1,2-diylbis(N,N-dimethyl-N-hexadecylammonium acetoxy)dichloride (16-E2-16) influences the micellization of promethazine hydrochloride (PMT) studied through surface tension, UV and FT-IR measurements in various media (aqueous, 50 mmol/kg sodium chloride (NaCl), 500 mmol/kg urea (U) and 500 mmol/kg thiourea (TU)) solutions. The solution and interfacial behavior show synergism between PMT and gemini surfactant in all the media. The addition of urea (U) and thiourea (TU) to the PMT, 16-E2-16, and PMT + 16-E2-16 mixture solution exhibit both increase and decrease in cmc hangs on concentration of [U] and [TU] and here the employed concentration of [U] or [TU] increases the cmc value of system while NaCl always decreases the cmc value. In mixed micelles, the micellar composition of 16-E2-16 is found higher than PMT. The micelle phase is found rich in surfactant monomers as compared to drug molecules. Activity coefficients in each case were attained below one in solution and interface, which authorized an interaction between constituents along with non-ideal behavior of mixtures. Different evaluated thermodynamic parameters depicted spontaneity as well as stability of mixed systems. UV–visible spectra showed that the absorption intensity of PMT increased with the addition of 16-E2-16 owing to interaction amongst them. FTIR investigation confirmed that the peak shifting in spectra of the pure component was detected also addressed the interaction amongst both components (PMT and 16-E2-16). Mixed micelles formation enhances solubility and permeability, so favorable for drug delivery purposes across the membrane.